It was in some form planned a LOT farther back than 2019. Putin really has been chewing on it since the Euromaidan event of 2014. He was ticked that they didn’t get more territory then... and that the international community, while not directly arming Ukraine, was supportive of them. And of course, the US’s covert support in that revolution against his puppet in the President’s Mansion...
“....since 2014, when a US-backed coup d’état saw the democratically elected president, Victor Yanukovich, ousted by neo-Nazi paramilitary groups.”
‘Checkmate: Putin’s Address Marks Game Over for Kiev’s US & NATO Backers, Analysts Say’
https://sputniknews.com/20220921/checkmate-putins-address-marks-game-over-for-kievs-us—nato-backers-analysts-say-1101056726.html